Syntheses, structures and luminescence behaviour of some zinc(II) complexes containing acetate and tetradentate Schiff bases / created by Ashis Kumar Maji, Subhasis Roy, Somnath Choubey, Rajarshi Ghosh and Barindra Kumar Ghosh

Two mononuclear compounds of the types pentacoordinated [Zn(L1)(OAc)]PF6⋅H2O (1) and hexacoordinated [Zn(L2)(OAc)]PF6 (2) [L1 = N,N -(bis(pyridin-2-yl)formylidene)-1,3-propanediamine; L2 = N,N -(bis(pyridin-2-yl)benzylidene)-1,4-butanediamine] have been synthesized using one-pot reactions of a 1:1:1 molar ratio of Zn(OAc)2.2H2O, L1/L2, ammonium hexafluorophosphate in MeOH at room temperature. Compounds 1 and 2 are characterized on the basis of microanalytical, spectroscopic, thermal and other physicochemical results. Single crystal X-ray structural study reveals that the zinc(II) centre in 1 is coordinated by four N atoms of the Schiff base L1 and one O atom of terminal acetate with a ZnN4O chromophore, whereas in 2, the zinc(II) centre is bound by four N atoms of the tailored Schiff base L2 and two O atoms of the chelated acetate. In the crystalline state, mononuclear units in 1 are engaged in weak cooperative intermolecular O-H ⋯O and C-H ⋯F hydrogen bonds affording a 1D chain. The individual units of 2 are packed by π⋯π and anion ⋯π interactions to form a 2D sheet structure. The complexes show reasonable thermal stabilities and display intraligand π→π ∗ fluorescence in solid state at room temperature.